Known drum drive elevator systems typically involve "cotton reel" type drum and lifting rope arrangements where the rope is wound onto the drum with successive turns such that each length of rope is placed adjacent to the prior length to form a single layer of wound rope. Such systems are usually limited to single layer rope winding because of safety and rope life considerations. In situations where the elevator car must travel over a large rise, the length of the drum required to accommodate single layer rope winding becomes impractical. Because of the length of the drum in such instances, large variations in the rope path occur as the rope is wound along the drum. This may cause difficulty in the placement of guidance sheaves and may result in changing direction of forces imposed on the elevator car thereby affecting ride quality.
In typical elevator systems, lifting force on an elevator car is delivered from a sheave located above the car. Without additional means of control, the lifting force could continue to be delivered until the elevator car impacts either the ceiling of the hoistway or the sheave. Thus, there exists the potential in conventional elevator systems having the drive sheave or drum located overheard that the elevator car may be accidentally driven through the top terminal. Special precautions are ordinarily required to ensure that drive force is disabled when the elevator car moves beyond the top terminal level. In traction elevator systems, for example, a deceleration zone and safety equipment such as a rope brake are required, adding cost and space consumption.
Conventional drum and traction elevator systems usually require a large machine room to accommodate the overhead machine and components, including safety features. It is desirable to eliminate the need for a large machine room and its associated costs and building structure requirements.